Referring to FIGS. 1 and 2, most of the prior art personal digital assistants (PDA) 1 or flat computers 11 are combined with compact flash (CF) memory cards or secure digital (SD) memory cards for storing data. The prior art memory card 10 installed with a blue tooth wireless communication module 12 has a function of blue tooth wireless communication. The personal digital assistant (PDA) 1 or flat computer 11 is further combined with a satellite receiver 13, a GSM communication module 14, and a GPRS communication module 15 for navigation of satellites and wireless communication. However, the interface slot of the personal digital assistant 1 only receives one memory card 10. To improve this defect, external interface slot is introduced so that a larger volume is required.
The various objects and advantages of the present invention will be more readily understood from the following detailed description when read in conjunction with the appended drawing.